close keep open?

pinewapple_2

So i had a capital one and aqua card to start building my credit rating being only 19, I was recently accepted for a much better card with natwest with 1500 limit. I also applied today for a mbna card today and was accepted with 1500 and 0% on purchases for 15/16 months. I closed the capital one and is now closed as i replaced it with the natwest one, The aqua card has a 1050 limit but only been open 7 months would it be best to close this as the mbna one is a much better deal. I applied for these 2 new cards natwest/mbna to replace the others as they are very high APR and these 2 are much much lower Would it be best to keep it open for a year then close it or just close if im not going to use it, just what is best for my credit history?

Was suprised to be accepted for these cards to as im just over 19 maybe the banks are starting to see me as more attractive
Thanks